Not applicable.
Not applicable.
The present invention is directed generally to the transmission of signals in optical communications systems. More particularly, the invention relates to optical communications systems including a branching unit and to associated devices and methods.
It is known to construct optical communications systems with one or more branch units to allow for connections to three or more locations. See, for example, U.S. Pat. No. 5,005,937, issued Apr. 9, 1991, U.S. Pat. No. 5,083,874, issued Jan. 28, 1992, and U.S. Pat. No. 5,214,312, issued May 25, 1993. Occasionally, power in a communications system must be reconfigured, such as in response to a cable cut or other failures. Branch units, as well as other parts of the system, often include electronic equipment to facilitate the power reconfiguration. That equipment can add significant expense to the branch unit and to other parts of the system. While the power is being reconfigured, traffic is typically dropped and communication through the affected parts of the system is interrupted.
In addition, the branch units and other parts of the system often include optical and electrical equipment for switching, amplifying or otherwise controlling traffic flow through the system. This equipment can be expensive and can add complexity to the system. Expense and complexity are typically undesired, particularly if the expense and complexity is for a relatively short segment between the branch unit and terminal equipment.
Accordingly, there is need for communications systems with branch units that allow for improved performance and lower cost.
The systems, devices, and methods of the present invention address the above-stated needs. The present invention is generally described in terms of undersea systems, although it is also applicable to other systems, such as terrestrial communications systems.
One embodiment of an optical communications system according to the present invention includes first terminal equipment, second terminal equipment, third terminal equipment, a first powered optical segment connected to the first terminal equipment and including at least one amplifier, a second powered optical segment connected to the second terminal equipment and including at least one amplifier, an unpowered optical segment connected to the third terminal equipment, and a branch unit connecting the first powered segment, the second powered segment, and the unpowered segment via passive, all-optical connections, and wherein the unpowered segment is pumped with optical energy through the branch unit from at least one of the amplifiers in the first and second powered segments.
Another embodiment of an optical communications system according to the present invention includes first terminal equipment, second terminal equipment, third terminal equipment, a first powered optical segment connected to the first terminal equipment and including at least one amplifier, a second powered optical segment connected to the second terminal equipment and including at least one amplifier, an unpowered optical segment connected to the third terminal equipment, and a branch unit connecting the first powered segment, the second powered segment, and the unpowered segment via passive, all-optical connections, and wherein the first powered segment and the unpowered segment are connected via an optical connection that is not connected to the second powered segment.
One embodiment of a method of transmitting optical communications signals according to the present invention includes transmitting first and second optical communications signals from first terminal equipment along a first powered segment, amplifying each of the first and second signals at least one time in the first powered segment, attenuating the first signal after the first powered segment, directing the first signal to a second powered segment, amplifying the first signal at least one time in the second powered segment, receiving the first signal at second terminal equipment, amplifying the second signal after the first powered segment, directing the second signal to an unpowered segment, and receiving the second signal at third terminal equipment.
These and other embodiments of the present invention will be described in the following detailed description. The present invention addresses the needs described above in the description of the background of the invention by providing improved systems, apparatuses, and methods. These advantages and others will become apparent from the following detailed description.